Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Substitution
Processing...

Code Generator

Language

Generated Code

const regex = /^(\s*- \[([0-9]+\.)+ [^]]+\]\(#)([^)]+)\)$/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('^(\\s*- \\[([0-9]+\\.)+ [^]]+\\]\\(#)([^)]+)\\)$', 'gm') const str = `- [1. Why ?](#1-why-) - [2. Compile tool](#2-compile-tool) - [3. compile command help](#3--compile-command-help) - [3.1. .framework-config environment variables](#31-framework-config-environment-variables) - [3.2. Template variables](#32-template-variables) - [3.3. Bash-tpl templating](#33-bash-tpl-templating) - [3.4. Bash-tpl macros](#34-bash-tpl-macros) - [3.4.1. dynamicTemplateDir](#341-dynamictemplatedir) - [3.4.2. dynamicSrcFile](#342-dynamicsrcfile) - [3.4.3. dynamicSrcDir](#343-dynamicsrcdir) - [3.5. directives and template](#35-directives-and-template) - [3.5.1. \`# FUNCTIONS\` directive](#351--functions-directive) - [3.5.2. \`VAR_*\` directive (optional)](#352-var_-directive-optional) - [3.5.3. \`BIN_FILE\` directive (optional)](#353-bin_file-directive-optional) - [3.5.5. \`EMBED\` directive (optional)](#355-embed-directive-optional) - [3.5.4. Compiler - Embed::embed](#354-compiler---embedembed) - [3.6. \`.framework-config\` framework configuration file](#36-framework-config-framework-configuration-file) - [4. FrameworkLint](#4-frameworklint) - [5. Best practices](#5-best-practices) - [6. Acknowledgements](#6-acknowledgements)`; const subst = `$1$4`; // The substituted value will be contained in the result variable const result = str.replace(regex, subst); console.log('Substitution result: ', result);

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions